Thermostatic controlling apparatus



Jan. 19, 1937. J. E. wAssoN THERMOSTATIC CONTROLLING APPARATUS Filed Feb. 14, 1954 INVENTOR.

TTORN Patented Jan. 19, 1937 UNITED STATES THERMOSTATIG CONTROLLING APPARATUS John E. Wasson, Boston, Mass, assignor to Emerson Apparatus Company, Melrose, Mass., a corporation of Rhode Island Application February 14, 1934, Serial No. 711,139

Claims.

It is sometimes desirable to control the operation of heating, ventilating, or other equipment, not directly in response topredetermined changes in temperature, as in the usual thermostatically 5 controlled apparatus, but in accordance with, or in response to, certain differences in temperature existing at different locations. In some cases such a control is useful in conjunction with the more common types of. temperature controls. To

devise an instrument which will satisfy these requirements constitutes the chief object of this invention.

The nature of the invention will be readily understood from the following description when read in connection with the accompanying drawing, and the novel features will be particularly pointed out in the appended claims.

In the drawing,

Figure 1 is a front elevation, with parts broken away, of an instrument embodying the invention;

and

Fig. 2 is a vertical, sectional view, partly in elevation, of the apparatus shown in Fig. l.

The instrument illustrated in the drawing comprises two thermostats indicated, respectively, at 2 and 3, each being substantially a duplicate of the other. Both are mounted in fixed positions on a base 4 of some suitable electrical insulating material, such as hard rubber, slate, or the like.

In the particular form shown, the upper thermostat 2 consists of a Bourdon tube secured to a hollow base block 5 from which lead two capil ry tubes, indicated at 6 and 1, respectively, the f mer being used simply for filling purposes, and

the latter being an armored tube running to a bulb 8. The elements 2, 5, 6, 'I and 8 are all in direct communication with each other, and are all filled with some suitable thermo -responsive fluid, the nature of which necessarily will de- 0 pend upon the requirements of diiferent uses to which the instrument will be put. For many purposes a light mineral oil is a satisfactory fluid medium. As is well understood by those skilled in this art, the Bourdon tube of a thermostat of this type has considerable inherent resiliency, and

when the temperature of the liquid medium with which it is filled rises, the pressure so created expands the tube, while a drop-in temperature of said medium permits the tube to contract. Since the volume of the liquid in the bulb 8 is several times the total of that contained in the parts 2, 5, 6 and I, the position taken by the free end of the Bourdon tube will be controlled almost entirely by the temperature of the liquid tin said bulb. A

The movement of the free end of the tube 2 is utilized to control the position of an electric contact I0 which is soldered to the lower end of a 1 plunger I2, mounted to slide in the vertical bore 60 of a stationary block l3 that is secured rigidly to the base 4. A coiled spring l4 encircles a reduced portion of said plunger and urges this plunger downwardly. Rigidly secured to the upper end of the plunger is a yoke IS, the cross bar of which rides on a rod l6 which is mounted on, and sup- 5 ported by, the forked end piece I! of the tube 2, the bar I6 being made of glass, porcelain, or some other anti-friction material. This arrangement enables the Bourdon tube to raise the plunger and the spring to lower it with relatively little re- 10 sistance due to the differences in the directions oftravel of the plunger and the end l'l.

Attached to the block I3 is a wire or electric conductor I8. Also, in order to improve the conduction between the contact l0 and the block J3, 15 a flexible metal strip 20, Fig. 2, is soldered at one end to the upper end of the plunger l2, extends I at right angles to the plunger to a point close to the base 4, and then is bent to project under the base where it is clamped by the screws that se- 20 cure the block to the base.

As above stated, the other thermostat 3 is substantially identical with that just described, and the corresponding parts are designated by the same, but primed, numerals. The two blocks [3 25 and [3' are so located that the plungers l0 and i0 are held in line with each other, but the plunger I2 is reversed with reference to the plunger l2. In other words, the lower plunger is normally pressed upward by the spring l4, and its contact 30 I0 is located on the upper end of it instead of on the lower end, as in the construction above described.

Preferably the two thermostats are filled under identical temperature and pressure conditions, 35 and they are so adjusted that when the two thermostats and their bulbs are at the same temperature, the contacts In and ID, will barely touch each other. Cosequently, at this timethe circuit a in which these contacts and the conductors I8 40 if the temperatures of the thermostats should drop to the same degree and at the same rate, both contacts would fall at substantially the same rate and to the same exteiit, but they would still remain closed. In other words, the two contacts follow each other upon either a rise in temperatures of both instruments, or a drop in their temperatures, but they may be separated by the differential expansion and contraction of the two thermostatic units. So long as the temperature of the upper thermostat remains equal to, or below that of, the lower unit, the circuit will be. kept closed, but when the temperature of the upper thermostat rises above that of the lower thermostat, then the circuit will open and it will remain open so long as this condition obtains.

Such an instrument finds an important use in cold storage plants where the temperature inside the plant is normally maintained below that of the outside atmosphere, the inside atmosphere, however, being kept at such a point, say for example, somewhere between 32 and F., that the outside temperature will at times drop below it. When such a drop in atmospheric temperature occurs, it is desirable, as a matter of economy, to shut off the refrigerating apparatus which maintains the inside temperature, and to start up a ventilating fan, open dampers, or to make some other adjustment for the purpose of circulating the outside atmosphere through the plant. The instrument shown can be used to automatically control the fans, dampers, or other apparatus required for this purpose. When used in such a relationship the bulb 8 will be located outside the building, or in some position where it responds to the temperature of the outside atmosphere, while the bulb 8 is placed inside the plant where it remains at substantially the inside temperature. Normally, or during most of the time, the outside temperature is higher than, that inside the plant, and consequently, the contacts In and ID are kept separated, and the control circuit remains open. When the outside temperature drops, however, to a point where it substantially equals the inside temperature, then the contacts Ill and II) are brought together and the circuit which they control is closed, thus bringing into operation the ventilating blowers or other equipment governed by said circuit. This condition will continue until the outside temperature again rises above the inside temperature, at which time the contacts will be automatically opened and the ventilating equipment will be out out of operation. When the control apparatus is used for this purpose it is designed to supplement the action of the ordinary control system used in such a plant.

, The instrument is also useful for'numerous other purposes.

Usually it is preferable to enclose the operating parts of the apparatus in order to protect them lrom'accidental injury, and for this purpose the base 4, and the parts mounted on it, may be secured in a box or casing 22 equipped with a hinged cover 23.

While I have herein shown and described a typical embodiment of my invention, it will be evident that the invention may be embodied in remain open so long as the temperature of the upper thermostat remains above, or does not drop more than a specified minimum below, that of the lower thermostat. When, however, the temperature of the'lower thermostat rises more than a certain specified maximum above that of the upper thermostat, the circuit will automatically close, this specified maximum being determined by the width of the gap separating the contacts when the temperatures of the two thermostats are equal.

Also, that the operation of Having thus described my invention, what I desire to claim as new is:

1. In an apparatus of the character described, the combination of two thermostats responsive to temperature changes in widely separated locations, and two contacts connected, respectively, with said thermostats and positioned for engagement with each other under certain temperature conditions, said thermostats being connected with said contacts to move both of them in the same direction and at substantially the same rate upon a rise in temperature at both of said locations and to move both contacts in the opposite direc tion and at substantially the same rate upon a drop in temperature at said locations.

2. In an apparatus of the character described, the combination of two thermostats responsive to temperature changes in widely separated 1ocations, each of said thermostats being substantially a duplicate of the other, and two contacts connected, respectively, with said thermostats and positioned for engagement with each other under certain minimum temperature differences at said locations, said thermostats being connected with said contacts to move both of them in the same direction and at substantially the same rate upon a rise in temperature at both of said locations and to move both contacts in the opposite direction and at substantially the same rate upon a drop in temperature at said locations.

3. In an apparatus of the character described, the combination of two thermostats responsive to temperature changes in widely separated locations, two electrical contacts connected, respectively, with said thermostats to be moved by them, and means supporting said contacts for sliding movement into and out of engagement with each other, said thermostats being connected with said contacts to move both of them in the same direction upon a rise in temperature at both of said locations and to move both contacts in the opposite direction upon a drop in temperature at said locations.

4. In an apparatus of the character described, the combination of two'thermostats responsive to temperature changes in widely separated locations, two electrical contacts connected, respectively, with said thermostats to be moved by them, means supportingsaid contacts for sliding movement into and out of engagement with each other, and two springs acting yieldingly on the respective contacts to move them toward each other, said thermostats being connected with said contacts to move both of them in the same direction upon a rise in temperature at both of said locations and to move both contacts in the opposite direction upon a drop in temperature at said locations.

5. In an apparatus of the character described, the combination of two thermostats responsive to temperature changes in widely separated locations, and two contacts connected, respectively, with said thermostats and positioned for engagement with each other under certain temperature conditions, said thermostats being connected with said contacts to move both of them in the same direction and at substantially the same rate upon a rise in temperature at both of said locations and to move both contacts in the opposite direction and at substantially the same rate upon a drop in temperature at said locations, and to move the contacts in opposite directions relative to each other, upon creation of a temperature differential between said locations.

JOHN E. WASSON. 

